BrightSource Energy of Oakland unveiled plans Friday to build a cluster of three solar power plants in the Southern California desert, a project capable of generating enough electricity for 300,000 homes.

The Rio Mesa project - near Blythe in Riverside County - would feature three fields of mirrors, each one surrounding a 750-foot-tall tower. The mirrors would focus sunlight on the towers, producing intense heat that would be used to boil water into steam, turn turbines and generate electricity.

The company on Friday submitted the project to the California Energy Commission for approval. Rio Mesa will also require a permit from the Bureau of Land Management, because part of the 5,750-acre project sits on federal land. Securing those permits will probably take more than a year, with construction lasting another 18 months.

BrightSource has already started construction on another massive solar complex, the Ivanpah Solar Electric Generating System, which when finished will generate up to 392 megawatts of electricity. Rio Mesa, in contrast, would produce a maximum of 750 megawatts from its three plants, combined.

BrightSource is building Ivanpah with the help of a $1.6 billion loan guarantee from the same federal program that funded Solyndra, the Fremont solar panel maker whose bankruptcy last month triggered a fierce debate over government support for renewable power. That program, however, issued its final loan commitments in September and won't be available for Rio Mesa.

BrightSource spokesman Keely Wachs said the company expects to find private financing for the project. Ivanpah won its government backing at a time when the financial markets were still recovering from the credit crisis.

"Clearly, things have improved since the credit market implosion in 2008," Wachs said. "But this project won't be financed for another year and a half, two years. It's premature to talk about financing for a project that hasn't been permitted."

The company did not disclose the expected cost of building Rio Mesa. Ivanpah will cost an estimated $2.2 billion.

The company in August filed plans for another solar complex, dubbed Hidden Hills, which would be capable of generating enough electricity for 178,000 homes.